JP2007132453A - Wheel bearing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel bearing unit at a fourth generation structure, which aims higher rigidity and improves a lightweight and compact design. <P>SOLUTION: A hub wheel 1 and an outer joint member 14 are plastically connected in the wheel bearing unit as a fourth generation structure. A double row of rolling bodies are provided with tapered rollers 6a and 6b having the same specifications. A pitch circle diameter PCDi at an inner side between pitch circle diameters PCDi and PCDo of the tapered rollers 6a and 6b is larger than the pitch circle diameter PCDo at an outer side, and the number of the tapered rollers 6b at the inner side is greater than that of the tapered rollers 6a at the outer side. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel bearing device for rotatably supporting a wheel of an automobile or the like with respect to a suspension device, and more particularly to a wheel bearing device having a fourth generation structure that achieves high rigidity and light weight and compactness. is there.

  The wheel bearing device for rotatably supporting the wheel of an automobile or the like is a second generation having a body mounting flange integrally with an outer member from a structure in which a double row rolling bearing called a first generation is used independently. Furthermore, the third generation in which one inner rolling surface of the double row rolling bearing is integrally formed on the outer periphery of the hub wheel integrally having the wheel mounting flange, and further, the constant velocity universal joint is provided on the hub wheel. Up to the fourth generation, in which the other inner rolling surface of the double row rolling bearing is integrally formed on the outer periphery of the outer joint member constituting the constant velocity universal joint.

  The wheel bearing device shown in FIG. 4 is a typical example of the fourth generation structure, but the hub wheel 50, the double row rolling bearing 60 and the constant velocity universal joint 70 are configured as a unit. The double-row rolling bearing 60 includes an outer member 51, an inner member 52, and double-row balls 53, 53 accommodated between the two members.

  The outer member 51 integrally has a vehicle body mounting flange 51b attached to a knuckle constituting a suspension device (not shown) on the outer periphery, and double row outer rolling surfaces 51a and 51a are formed on the inner periphery. On the other hand, the inner member 52 includes a hub wheel 50 and an outer joint member 71 (described later) fitted into the hub wheel 50.

  The hub wheel 50 integrally has a wheel mounting flange 54 for mounting a wheel (not shown) at one end, and one inner rolling surface 50a facing the double row outer rolling surfaces 51a, 51a on the outer periphery. And the cylindrical small diameter step part 50b extended in an axial direction from this inner side rolling surface 50a is formed. Hub bolts 54 a are implanted in the circumferential direction of the wheel mounting flanges 54. And the surface hardness is hardened in the range of 58-64 HRC by induction hardening over the inner rolling surface 50a and the small diameter step portion 50b from the seal land portion in which the outer seal 57 is in sliding contact.

  Further, an uneven portion 55 is formed on the inner periphery of the hub wheel 50, and the surface is hardened to a predetermined surface hardness by induction hardening. The concavo-convex portion 55 is formed in an iris knurl shape, and is composed of a cross groove formed by a plurality of annular grooves formed independently by turning or the like and a plurality of axial grooves formed by broaching or the like substantially orthogonal to each other. .

  The constant velocity universal joint 70 includes an outer joint member 71, a joint inner ring 72, a cage 73, and a torque transmission ball 74. The outer joint member 71 is integrally formed with a cup-shaped mouth portion 75, a shoulder portion 76 that forms the bottom of the mouth portion 75, and a cylindrical shaft portion 77 that extends from the shoulder portion 76 in the axial direction. The shaft portion 77 is formed with an in-row portion 77a that is cylindrically fitted to the small-diameter step portion 50b of the hub wheel 50 via a predetermined radial clearance, and a fitting portion 77b is formed at the end of the in-row portion 77a. .

  On the outer periphery of the shoulder portion 76, the other inner rolling surface 71a facing the double row outer rolling surfaces 51a, 51a of the outer member 51 is formed. Then, the surface hardness is set to a range of 58 to 64 HRC by induction hardening over the inner rolling surface 71a and the shaft portion 77 from the seal land portion in which the inner seal 58 is in sliding contact. Here, the fitting part 77b is left raw after forging.

In assembling the hub wheel 50, the double row rolling bearing 60, and the constant velocity universal joint 70, first, the balls 53 are temporarily assembled to the double row outer rolling surfaces 51a, 51a of the outer member 51 via the retainers 56, respectively. Is done. Next, the shoulder portion 76 of the outer joint member 71 is abutted against the end face of the small-diameter stepped portion 50b of the hub wheel 50, and the shaft portion 77 is fitted into the hub wheel 50 until it comes into a butted state. Further, a diameter expanding jig such as a mandrel is pushed into the inner diameter of the fitting portion 77b in the shaft portion 77 to increase the diameter of the fitting portion 77b, and the fitting portion 77b is bitten into the uneven portion 55 of the hub wheel 50. It is performed by caulking and plastically coupling the hub wheel 50 and the outer joint member 71 together. Such a fourth generation structure can reduce the weight and size of the wheel bearing device, and can provide a wheel bearing device having a coupling portion that does not loosen.
Japanese Patent Laid-Open No. 2001-18605

  In such a conventional wheel bearing device, it is desired to exhibit sufficient strength and durability even when a large moment load or the like is applied, and to increase the bearing rigidity for stable running. However, there is almost no room to increase the size of the device if there is not enough space, and the bearing rigidity is further increased while reducing weight and size in order to improve vehicle performance by improving vehicle fuel efficiency and reducing unsprung weight. It is difficult to increase.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a wheel bearing device having a fourth generation structure that is lightweight and compact in addition to high rigidity.

  In order to achieve such an object, the invention according to claim 1 of the present invention is a wheel bearing device in which a hub wheel, a double row rolling bearing, and a constant velocity universal joint are unitized. The rolling bearing has an outer member in which a double row outer rolling surface is formed on the inner periphery, and a wheel mounting flange integrally formed at one end, and one end facing the outer rolling surface of the double row on the outer periphery. A hub ring formed with an inner rolling surface and a cylindrical small-diameter stepped portion extending in the axial direction from the inner rolling surface, and is fitted into the hub ring and faces the double-row outer rolling surface on the outer periphery. An inner member composed of an outer joint member of the constant velocity universal joint integrally formed with the other inner rolling surface, and a shaft portion extending in the axial direction from the inner rolling surface, and the inner member and the outer member. A plurality of rolling elements accommodated in a freely rolling manner between both rolling surfaces of the side member, and the end of the shaft portion is plastically deformed. In the wheel bearing device in which the hub wheel and the outer joint member are integrally plastically coupled by caulking to the hub wheel, the pitch circle diameter is different between the outer side and the inner side of the double row rolling elements. In addition, a configuration was adopted in which the number of rolling elements on the large diameter side of the pitch circle diameter was set larger than the number of rolling elements on the small diameter side.

  Thus, in the wheel bearing device of the fourth generation structure in which the hub wheel and the outer joint member constituting the constant velocity universal joint are unitized by plastic coupling, the outer side and the inner side of the double row rolling elements, The pitch circle diameter is different, and the number of rolling elements on the large diameter side is larger than the number of rolling elements on the small diameter side. A wheel bearing device can be provided.

  Preferably, as in the invention described in claim 2, a hardened uneven portion is formed on the inner diameter of the hub wheel, and the hollow fitting portion formed in the shaft portion is expanded in diameter to form the uneven portion. If the hub wheel and the outer joint member are integrally plastically joined by biting, there is no need to manage the preload by tightening firmly with a nut or the like, and the weight and size can be reduced. The strength and durability of the hub wheel can be improved and the preload amount can be maintained for a long time.

  The invention according to claim 3 can ensure high rigidity if at least the rolling element having a smaller pitch circle diameter is a tapered roller among the double row rolling elements.

  Further, as in the invention described in claim 4, if the double row rolling elements are tapered rollers of the same specification, the problem of wrong assembly in the assembly process can be solved, the manufacturing cost can be reduced, and the quality can be reduced. Reliability is improved.

  Further, as in the fifth aspect of the invention, if the rolling element having a larger pitch circle diameter is a ball among the rolling elements in the double row, the load capacity or rigidity balance of the double row bearing row is balanced. The device can be made more compact in the axial direction while maintaining.

  A wheel bearing device according to the present invention is a wheel bearing device in which a hub wheel, a double row rolling bearing, and a constant velocity universal joint are unitized, and the double row rolling bearing has a double row on an inner periphery. An outer rolling surface formed with the outer rolling surface, a wheel mounting flange at one end, and an inner rolling surface facing the double row outer rolling surface on the outer periphery, and the inner rolling surface. A hub wheel formed with a cylindrical small-diameter step portion extending in the axial direction from the running surface, and the other inner rolling surface that is fitted in the hub wheel and faces the outer surface of the double row on the outer periphery; An inner member composed of an outer joint member of the constant velocity universal joint integrally formed with a shaft portion extending in the axial direction from the inner rolling surface, and between both rolling surfaces of the inner member and the outer member. A plurality of rolling elements accommodated in a freely rolling manner, and plastically deforming an end portion of the shaft portion to crimp the hub ring. Further, in the wheel bearing device in which the hub wheel and the outer joint member are integrally plastically coupled, the pitch circle diameter is different between the outer side and the inner side of the double row rolling elements, and the pitch circle diameter is large. Since the number of the rolling elements on the diameter side is set to be larger than the number of the rolling elements on the small diameter side, it is possible to provide a wheel bearing device that achieves high rigidity and light weight and compactness.

  A wheel bearing device in which a hub wheel, a double row rolling bearing, and a constant velocity universal joint are unitized, wherein the double row rolling bearing has an outer periphery formed with a double row outer rolling surface. And a cylindrical member extending in the axial direction from the inner rolling surface, and one inner rolling surface facing the outer rolling surface of the double row on the outer periphery. A hub wheel having a small-diameter stepped portion, the other inner rolling surface that is fitted into the hub wheel and faces the outer rolling surface of the double row on the outer periphery, and extends axially from the inner rolling surface An inner member composed of an outer joint member of the constant velocity universal joint having a cylindrical shaft portion formed integrally, and is accommodated in a freely rollable manner between both rolling surfaces of the inner member and the outer member. A plurality of rolling elements, a hardened uneven portion is formed on the inner diameter of the hub wheel, and the fitting portion formed on the shaft portion is expanded. In the wheel bearing device in which the hub wheel and the outer joint member are integrally plastically joined by biting into the concave and convex portions, the double row rolling elements are composed of tapered rollers of the same specification. Among the pitch circle diameters of the rollers, the inner side has a larger diameter than the outer side, and the number of the tapered rollers is set larger.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a first embodiment of a wheel bearing device according to the present invention. In the following description, the side closer to the outer side of the vehicle in a state assembled to the vehicle is referred to as the outer side (left side in the drawing), and the side closer to the center is referred to as the inner side (right side in the drawing).

  In this wheel bearing device, a hub wheel 1, a double row rolling bearing 2 and a constant velocity universal joint 3 are configured as a unit. The double row rolling bearing 2 includes an outer member 4, an inner member 5, and double row rolling elements (conical rollers) 6a and 6b. The inner member 5 includes a hub wheel 1 and an outer joint member 14 fitted in the hub wheel 1.

  The outer member 4 is made of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and integrally has a vehicle body mounting flange 4c for mounting to the vehicle body (not shown) on the outer periphery. Tapered double row outer rolling surfaces 4a and 4b are formed. The double row outer raceway surfaces 4a and 4b are hardened by induction hardening to a surface hardness of 58 to 64 HRC.

  On the other hand, the hub wheel 1 is made of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and has a wheel mounting flange 7 for mounting a wheel to an end portion on the outer side. A plurality of hub bolts 8 are planted at equal intervals in the circumferential direction. Further, on the outer circumference of the hub wheel 1, one (outer side) tapered inner rolling surface 1a facing the double row outer rolling surfaces 4a and 4b, and the inner rolling surface 1a in the axial direction. An extending cylindrical small-diameter step portion 1b is formed. And the surface hardness is hardened in the range of 58-64 HRC by induction hardening over the inner rolling surface 1a and the small diameter step portion 1b from the seal land portion 7a with which the outer seal 10 is in sliding contact. As a result, not only the wear resistance of the seal land portion 7a serving as the base portion of the wheel mounting flange 7 is improved, but also the hub has sufficient mechanical strength against the rotational bending load applied to the wheel mounting flange 7. The durability of the wheel 1 is improved.

  Concave and convex portions 12 are formed on the inner periphery of the hub wheel 1, and the surface is hardened by heat treatment so that the surface hardness is in the range of 54 to 64 HRC. As the heat treatment, local heating is preferable, and quenching by high-frequency induction heating that can set the hardened layer depth relatively easily is preferable. The concave and convex portion 12 is formed in the shape of an iris knurl, and is a cross groove formed by a plurality of annular grooves formed independently by turning or the like and a plurality of axial grooves formed by broaching or the like substantially orthogonal to each other. Alternatively, it consists of a cross groove composed of spiral grooves inclined with respect to each other. Further, in order to ensure good biting property, the tip of the concavo-convex portion 12 has a spire shape such as a triangular shape.

  The constant velocity universal joint 3 includes an outer joint member 14, a joint inner ring 15, a cage 16, and a torque transmission ball 17. The outer joint member 14 is made of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and has a cup-shaped mouth portion 18, a shoulder portion 19 that forms the bottom portion of the mouth portion 18, and the shoulder portion 19. And a cylindrical shaft portion 20 extending in the axial direction are integrally formed. The shaft portion 20 is formed with an in-row portion 20a that is cylindrically fitted to the small-diameter step portion 1b of the hub wheel 1 through a predetermined radial clearance, and a fitting portion 20b is formed at the end of the in-row portion 20a. .

  A curved track groove 18 a extending in the axial direction is formed on the inner periphery of the mouse portion 18, and a track groove 15 a corresponding to the track groove 18 a is formed on the outer periphery of the joint inner ring 15. A torque transmission ball 17 is accommodated between the track grooves 18a and 15a via a cage 16. Further, on the outer periphery of the shoulder portion 19, the other (inner side) tapered inner rolling surface 14a facing the double row outer rolling surfaces 4a, 4b is formed. Then, the surface hardness is set to a range of 58 to 64 HRC by induction hardening over the inner rolling surface 14a and the shaft portion 20 from the seal fitting portion where the track groove 18a and the inboard-side seal 11 are in sliding contact with each other. ing. Here, the fitting part 20b of the shaft part 20 is left raw after forging.

  Double row rolling elements 6a and 6b are accommodated between the double row outer raceway surfaces 4a and 4b of the outer member 4 and the double row inner raceway surfaces 1a and 14a opposite to these, and the cage 9a, 9b is rotatably held. Further, seals 10 and 11 are attached to the end portion of the outer member 4 to prevent leakage of the lubricating grease sealed inside the bearing and intrusion of rainwater, dust and the like into the bearing from the outside. These double-row rolling bearings 2 are so-called back-to-back type double-row cones in which the action lines of the acting directions of the forces applied to the rolling surfaces 4a, 1a and 4b, 14a are separated in the axial direction as they approach the axial center. It constitutes a roller bearing.

  In the present embodiment, the pitch circle diameter PCDi of the inner side rolling element 6b is set larger than the pitch circle diameter PCDo of the outer side rolling element 6a. The specifications of these double-row rolling elements 6a and 6b are the same, but due to the difference in pitch circle diameters PCDo and PCDi, the number of inner-side rolling elements 6b is set larger than the number of outer-side rolling elements 6a. ing. Here, the specifications of the rolling elements 6a and 6b refer to the roller length, the roller outer diameter, the roller angle, and the radius of curvature of the large roller end surface in the tapered roller. In the case of this type of double row tapered roller bearing, the specifications of the outer side rolling element 6a and the inner side rolling element 6b remain the same, that is, without changing the roller angle in the tapered roller and the radius of curvature of the roller large end face. In the case where the pitch circle diameters PCDo and PCDi are made different on the left and right, it is established by making the angles of the respective rolling surfaces different on the left and right. In the case of this embodiment, by making the specifications of the double row rolling elements 6a and 6b the same, it is possible to eliminate the problem of misassembly in the assembly process, reduce the manufacturing cost, and improve the reliability of the quality. To do.

  Thus, with the difference in pitch circle diameters PCDo and PCDi, the inner rolling surface 14a of the outer joint member 14 is formed with a larger diameter than the inner rolling surface 1a of the hub wheel 1 in the inner member 5. Yes. On the other hand, in the outer member 4, the outer side rolling surface 4 b on the inner side is formed with a larger diameter than the outer side rolling surface 4 a on the outer side with the difference in pitch circle diameters PCDo and PCDi.

  In the wheel bearing device having such a configuration, the inner-side inner rolling surface 14a is directly formed on the outer periphery of the shoulder portion 19 of the outer joint member 14, so that the pitch circle diameter PCDi of the inner-side rolling element 6b is set to the outer diameter. The pitch circle diameter PCDo of the rolling element 6a on the side can be set to a larger diameter, and the number of rolling elements 6b can be set to be larger than that on the outer side, making it lightweight and compact. In addition, the bearing rigidity of the inner side portion can be increased compared to the outer side, and the life of the bearing can be extended.

  Here, the unitization of the hub wheel 1, the double row rolling bearing 2 and the constant velocity universal joint 3 will be described. First, the double row rolling elements 6a and 6b are temporarily assembled on the double row outer rolling surfaces 4a and 4b of the outer member 4 via the cages 9a and 9b, and seals are provided at both ends of the outer member 4. 10 and 11 are mounted. Next, the outer joint member 14 is inserted from the inner side, the shoulder 19 of the outer joint member 14 is abutted against the end surface of the small-diameter step portion 1b of the hub wheel 1, and the hub wheel 1 is pivoted until it comes into a butted state. The part 20 is fitted inside. Then, a diameter expanding jig such as a mandrel is pushed into the inner diameter of the fitting portion 20b in the shaft portion 20 to increase the diameter of the fitting portion 20b, and the fitting portion 20b is bitten into the uneven portion 12 of the hub wheel 1. By caulking, the hub wheel 1 and the outer joint member 14 are integrally plastically joined to complete. As a result, it is not necessary to control the preload by tightening firmly with a nut or the like as in the prior art, so that the weight and size can be reduced and the strength and durability of the hub wheel 1 can be improved and long. The amount of preload can be maintained for a period. End caps 13a and 13b are attached to the opening end of the hub wheel 1 and the hollow shaft portion 20 to prevent rainwater or the like from entering the plastic coupling portion and rusting the portion, and the mouse portion. The grease sealed in 18 is prevented from leaking outside.

  When the double-row rolling bearing 2 is composed of a double-row tapered roller bearing, it is difficult to secure a stable bearing internal clearance in the diameter expansion caulking process. That is, when the bearing is assembled, the rolling elements 6a and 6b made of tapered rollers rub against each other in the generatrix direction of the rolling surfaces. For this reason, the lubricant such as grease is retracted from the abutting portions between these surfaces to be close to the metal contact, and the friction coefficient of these abutting portions is increased. For this reason, the rolling elements 6a and 6b are assembled in an unaligned state without smoothly moving to the guide to which the rolling elements 6a and 6b are guided. For example, even when this internal clearance should be negative, the positive internal clearance remains, and there is a possibility that a desired preload cannot be applied. In particular, when a so-called skew occurs in which the central axis of the rolling elements 6a and 6b made of tapered rollers is inclined with respect to the normal rotation axis, such a problem becomes remarkable.

  In the present embodiment, in order to avoid such a problem, the hub wheel 1, the outer joint member 14, and the outer member 4 are relatively swung (reciprocating) or rotated (one) in the diameter expansion caulking process. Direction) and plastic bonding is performed. In practice, with the hub wheel 1 supported on the upper surface of the work table, the diameter expansion jig is pushed into the shaft portion 20 of the outer joint member 14 while the outer member 4 is swung with respect to the hub wheel 1. The two are plastically connected. By doing so, the double-row rolling elements 6a and 6b are smoothly rubbed on the respective rolling surfaces and stably aligned, and a predetermined preload can be applied with high accuracy.

  In addition to the configuration exemplified as means for plastically coupling the hub wheel 1 and the outer joint member 14, for example, although not shown, the shaft portion of the outer joint member is fitted into the hub wheel, and the shaft portion A so-called swing caulking method may be employed in which the end portion is plastically deformed radially outward to form a caulking portion, and both members are fixed in the axial direction by the caulking portion.

  Further, here, the double row tapered roller bearing using the tapered rollers as the rolling elements 6a and 6b is illustrated as the double row rolling bearing 2, but the present invention is not limited to this, and for example, balls are used as the rolling elements 6a and 6b. It may be a double row angular contact ball bearing.

  FIG. 2 is a longitudinal sectional view showing a second embodiment of the wheel bearing device according to the present invention. This embodiment is different from the above-described embodiment only in the configuration of the inner-side bearing row, and other parts having the same parts or the same functions as those of the above-described embodiment are denoted by the same reference numerals and the details thereof are described. The detailed explanation is omitted.

  In this wheel bearing device, the hub wheel 1, the double row rolling bearing 21 and the constant velocity universal joint 22 are configured as a unit. The double row rolling bearing 21 includes an outer member 23, an inner member 24, and double row rolling elements 6 a and 25. The inward member 24 includes the hub wheel 1 and an outer joint member 26 fitted in the hub wheel 1.

  The outer member 23 is made of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and integrally has a vehicle body mounting flange 4c for mounting to a vehicle body (not shown) on the outer periphery. A tapered outer outer rolling surface 4a and an arcuate inner outer rolling surface 23a are formed. The double row outer rolling surfaces 4a and 23a are hardened by induction hardening to a surface hardness of 58 to 64 HRC.

  The outer joint member 26 of the constant velocity universal joint 22 is made of medium carbon steel containing carbon 0.40 to 0.80 wt% such as S53C, and has a cup-shaped mouth portion 18 and a shoulder portion 27 that forms the bottom portion of the mouth portion 18. The cylindrical shaft portion 20 extending in the axial direction from the shoulder portion 27 is integrally formed. And the inner side inner rolling surface 26a which opposes the outer side rolling surface 23a of the outer member 23 is directly formed in the outer periphery of the shoulder part 27, and the double row outer side rolling surfaces 4a and 23a of the outer member 23 are formed. The double-row rolling elements 6a and 25 are accommodated between the double-row inner rolling surfaces 1a and 26a of the inner member 24 facing the inner members 24, and are held by the cages 9a and 28 so as to be freely rollable.

  In the present embodiment, the pitch circle diameter PCDi of the inner side rolling element (ball) 25 is set larger than the pitch circle diameter PCDo of the outer side rolling element 6a. Due to the difference between the pitch circle diameters PCDo and PCDi, the number of inner side rolling elements 25 is set to be larger than the number of outer side rolling elements 6a.

  In the wheel bearing device having such a configuration, the inner side bearing row is constituted by the rolling elements 25 made of balls, and the inner side inner rolling surface 26 a is formed directly on the outer periphery of the shoulder portion 27 of the outer joint member 26. Therefore, the pitch circle diameter PCDi of the inner side rolling element 6b can be set larger than the pitch circle diameter PCDo of the outer side rolling element 6a, and the number of rolling elements 25 is also equal to the number on the inner side. Since it is set more than the outer side, the apparatus can be made more compact in the axial direction while maintaining the balance of load capacity or rigidity of the double row bearing rows.

  FIG. 3 is a longitudinal sectional view showing a third embodiment of the wheel bearing device according to the present invention. In this embodiment, only the configuration of the left and right bearing rows is opposite to that of the second embodiment (FIG. 2) described above, and other parts having the same parts or the same functions are denoted by the same reference numerals. A detailed description thereof will be omitted.

  In this wheel bearing device, the hub wheel 29, the double row rolling bearing 30 and the constant velocity universal joint 3 are configured as a unit. The double-row rolling bearing 30 includes an outer member 31, an inner member 32, and double-row rolling elements 33 and 6b. The inner member 32 includes a hub wheel 29 and the outer joint member 14 fitted in the hub wheel 29.

  The outer member 31 is made of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and integrally has a vehicle body mounting flange 4c for mounting to a vehicle body (not shown) on the outer periphery. The outer side rolling surface 31a on the outer side of the arc shape and the outer side rolling surface 4b on the tapered inner side are formed. The double row outer rolling surfaces 31a and 4b are hardened by induction hardening in a range of 58 to 64 HRC.

  The hub wheel 29 is made of medium carbon steel containing 0.40 to 0.80 wt% of carbon, such as S53C, and has one arcuate (outer side) arcuate shape on the outer periphery facing the double row outer raceway surfaces 31a and 4b. An inner rolling surface 29a and a cylindrical small diameter step portion 29b extending in the axial direction from the inner rolling surface 29a are formed. And the surface hardness is hardened in the range of 58-64 HRC by induction hardening over the inner rolling surface 29a and the small diameter step portion 29b from the seal land portion 7a with which the outer seal 10 is in sliding contact.

  Double row rolling elements 33, 6b are accommodated between the double row outer rolling surfaces 31a, 4b of the outer member 31 and the double row inner rolling surfaces 29a, 14a of the inner member 32 opposed thereto. The holders 34 and 9b are rotatably held.

  In the present embodiment, the pitch circle diameter PCDo of the outer side rolling element (ball) 33 is set larger than the pitch circle diameter PCDi of the inner side rolling element 6b. Due to the difference between the pitch circle diameters PCDo and PCDi, the number of outer rolling elements 33 is set to be larger than the number of inner rolling elements 6b.

  In the wheel bearing device having such a configuration, the outer bearing row is a rolling element 33 made of balls, and the pitch circle diameter PCDo of the outer rolling element 33 is larger than the pitch circle diameter PCDi of the inner rolling element 6b. Since the number of rolling elements 33 on the outer side is set to be larger than the number of inners, the device is compact in the axial direction while maintaining the load capacity or rigidity balance of the double row bearing rows. Can be

  The embodiment of the present invention has been described above, but the present invention is not limited to such an embodiment, and is merely an example, and various modifications can be made without departing from the scope of the present invention. Of course, the scope of the present invention is indicated by the description of the scope of claims, and further, the equivalent meanings described in the scope of claims and all modifications within the scope of the scope of the present invention are included. Including.

  The wheel bearing device according to the present invention can be applied to a wheel bearing device having a fourth generation structure in which a hub wheel, a double row rolling bearing, and a constant velocity universal joint are unitized.

It is a longitudinal section showing a 1st embodiment of a bearing device for wheels concerning the present invention. It is a longitudinal cross-sectional view which shows 2nd Embodiment of the wheel bearing apparatus which concerns on this invention. It is a longitudinal cross-sectional view which shows 3rd Embodiment of the wheel bearing apparatus which concerns on this invention. It is a longitudinal cross-sectional view which shows the conventional wheel bearing apparatus.

Explanation of symbols

1, 29 ································· Hub wheel 1a, 14a, 26a, 29a .....・ ・ ・ ・ ・ Small diameter step 2, 21, 30 ... Double row rolling bearings 3, 22 ... Constant velocity universal joints 4, 23, 31 ... Outer members 4a, 4b, 23a, 31a ... Outer rolling surface 4c ... ..... Body mounting flanges 5, 24, 32 ..... Inward members 6a, 6b, 25, 33 ...・ ・ Rolling element 7 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Wheel mounting flange 7a ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Seal land 8 ........... hub bolt 9a, b, 28, 34 ················ 10 ... Inner side seal 12 ... Uneven portions 13a, 13b ... End Caps 14, 26 ... outer joint member 15 ... joint inner rings 15a, 18a ...・ ・ ・ ・ ・ ・ ・ ・ ・ Track groove 16 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Cage 17 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・Torque transmitting ball 18 ........... Mouse part 19, 27 ..... Shoulder part 20 ... ..... Shaft 20a ... ... In-row part 20b ..... Fitting part 50 ... Hub wheel 50a, 71a ..... Inner rolling surface 50b ..... Small diameter step 51 ...・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Outer member 51a ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Outer rolling surface 51b ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・Car body mounting flange 52 ... Inner member 53 ... Ball 54 ... Wheel mounting flange 54a ... Hub bolt 55 ... ··································· 56 ... Outer seal 58 ... Inner seal 60 ...・ ・ ・ ・ ・ ・ ・ ・ ・ Double row rolling bearing 70 ・ ・ ・ ・ ・ ・ ・ ・ Constant velocity universal joint 71 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・Outer joint member 72 ... Fitting inner ring 73 ...・ ・ ・ ・ Cage 74 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Torque transmission ball 75 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Mouse part 76 ・・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Shoulder 77 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Shaft 77a ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・... In-row part 77b ......... Fitting part PCDi ... Pitch circle diameter PCDo ················ pitch circle diameter of the outer side of the rolling element of ............. inner side of the rolling elements

Claims (5)

A wheel bearing device in which a hub wheel, a double row rolling bearing and a constant velocity universal joint are unitized,
The double row rolling bearing is an outer member in which a double row outer rolling surface is formed on the inner periphery,
One end has a wheel mounting flange integrally, and on the outer periphery is one inner rolling surface facing the double row outer rolling surface, and a cylindrical small-diameter step portion extending in the axial direction from the inner rolling surface. The formed hub wheel, the other inner rolling surface that is fitted in the hub wheel and faces the outer rolling surface of the double row, and the shaft portion that extends in the axial direction from the inner rolling surface are integrated. An inner member made of an outer joint member of the constant velocity universal joint formed on
The inner member and a double row rolling element accommodated between the rolling surfaces of the inner member and the outer member so as to roll freely are provided, and the end of the shaft portion is plastically deformed to be fastened to the hub wheel. In the wheel bearing device in which the hub wheel and the outer joint member are integrally plastically coupled,
Among the double row rolling elements, the pitch circle diameter is different between the outer side and the inner side, and the number of rolling elements on the large diameter side is set larger than the number of rolling elements on the small diameter side. A wheel bearing device characterized by that.   A hardened concave and convex portion is formed on the inner diameter of the hub wheel, and the hub wheel and the outer joint member are formed by enlarging the hollow fitting portion formed in the shaft portion and biting into the concave and convex portion. The wheel bearing device according to claim 1, wherein the wheel bearing device is integrally plastic-bonded.   3. The wheel bearing device according to claim 1, wherein at least the rolling elements having a smaller pitch circle diameter of the double row rolling elements are tapered rollers. 4.   The wheel bearing device according to claim 3, wherein the double row rolling elements are tapered rollers of the same specification.   4. The wheel bearing device according to claim 3, wherein a rolling element having a larger pitch circle diameter of the double row rolling elements is a ball. 5.

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